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A173237 Alternate n and 10n for each n. 0
1, 10, 2, 20, 3, 30, 4, 40, 5, 50, 6, 60, 7, 70, 8, 80, 9, 90, 10, 100, 11, 110, 12, 120, 13, 130, 14, 140, 15, 150, 16, 160, 17, 170, 18, 180, 19, 190, 20, 200, 21, 210, 22, 220, 23, 230, 24, 240, 25, 250, 26, 260, 27, 270, 28, 280, 29, 290, 30, 300, 31, 310, 32, 320, 33 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..65.

Index entries for linear recurrences with constant coefficients, signature (0,2,0,-1).

FORMULA

a(n)=(1/4)*(11*n+9*n*(-1)^n+1+(-1)^(n-1)). [Paolo P. Lava, Apr 16 2010]

G.f.: x*(1+10*x) / ( (x-1)^2*(1+x)^2 ). - R. J. Mathar, Jun 18 2014

CROSSREFS

Cf. A008592, A101233.

Sequence in context: A005483 A228276 A040099 * A086068 A262557 A030595

Adjacent sequences:  A173234 A173235 A173236 * A173238 A173239 A173240

KEYWORD

nonn,easy

AUTHOR

Mark Dols, Feb 13 2010

STATUS

approved

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Last modified August 21 13:36 EDT 2017. Contains 290890 sequences.